We have two systems of classical music in India.One is the North Indian classical ( Hindustani classical) and the other is theSouth Indian classical traditions ( called Carnatic Classical).

In both some ragas are the same, Kalyan ( Hindustani) and Kalyani (Carnatic) are both the same raga. A romantic raga which is / should be sung only late evenings. Hindustani classical strictly follows the theory of time and season.

We can't sing a morning raga in the evening and a night raga can only be sung or played at night. We have ragas that are for spring, hot seasons, monsoons etc etc . . .

The theorists believe the raga gets its full potential only when sung, played or listened during the time it is allotted. But not always is that possible. Plus you need to have the whole chart of ragas ( several hundreds - each having their own time slot etc etc!) can be too confusing for a lay person.